Ok, heres the problem. My truck just started making this crackling sound almost like it is thin metal tapping or even sounds like electrical sparks popping. it only happens when i am in gear and driving. it is coming from somewhere from the tranny to the rear end. sometimes it goes away for a while but then sometimes it will be there all day. When i accelerate the noise increases with the acceleration. Now on to the vibrating. When i am driving on the express way above 65 mph and i let of the gas it almost sounds like i have an engine brake from a deisel on my truck. when i get on the gas again i can feel a clunk almost like there is something loose in the rear end. if anyone can help that would be greatly appreciated. The cracking/popping noise is my main concern. i have never heard that noise before on a vehicle other than electrical arching.

Thank you.

 

First thing to check would be the u-joints.

 

Well I took the rear end cover off and I had someone shift it from drive and then into reverse and I could see the pinion gear moving up and down about an 1/8 inch either way. Could it be the bearing on the pinion gear gone bad?